1. Field of the Invention
This invention relates generally to coverings for architectural openings and more particularly to an improved vane that may be used in a vertical window blind, door blind, or to otherwise furnish the interior of a dwelling.
2. Description of the Known Art
Vertical blinds have been known in the art for some time. A typical vertical blind has a headrail that contains a carrier mechanism, a tilt rod, and a plurality of operatively interconnected vertical vanes. The carrier mechanism includes a plurality of hangers for individually suspending the vertical vanes. The carrier mechanism is coupled to the tilt rod so that when the tilt rod is rotated the hangers are caused to rotate about vertical axes which in turn rotate the vertical vanes to which they are attached about the same axes. The vanes are always hung from their top edge with the hangers being undesirably visible or requiring a valence to cover them up.
Vanes for vertical window blinds are typically made with one or more of four different types of materials. These materials are fabric, polyvinylchloride (PVC), aluminum and wood. The most common vanes are made from either fabric, PVC or a combination of fabric and PVC. Fabric vanes offer a very appealing softer appearance. The fabric adds quality to a vane and gives it a finished look. It also provides a designer with a number of design choices regarding the type of fabric to use for a particular room. PVC vanes are plastic and therefor have a harder plastic appearance. One advantage of the PVC vane, however, is its strength. PVC vanes can be laminated or wrapped with fabric to provide the PVC strength with the fabric appearance.
There are disadvantages, however, to vanes made of fabric, PVC or combinations thereof. Vanes made solely of fabric are thin, and tend to twist along their length when rotated from the top edge. They further are substantially two dimensional. PVC vanes also tend to twist along their length when rotated from the top edge. The PVC vanes are also normally thin, even though they can be molded to provide a three dimensional shape. This shape is usually curved in cross-section, e.g. a C-shape or an S-shape, and the thickness of the vane is usually about 1/8 inch or less. Additional thickness is too costly for the window blind market.
Several hybrids exist for fabric vertical vanes. Fabric vanes are often treated with a stiffener to impart structural rigidity. The stiffener takes away the fabric's hand or softness, but retains the look of the fabric. The vane will still twist, but less than non-treated fabric vanes. The treated fabric vanes also tend to curl in direct sunlight if the stiffener is not applied uniformly. Another hybrid, as mentioned previously, is a PVC vane laminated with a fabric. Such a vane has the structural strength and three-dimensionality offered by a PVC vane with the appearance of a fabric vane. The fabric in this case also looses its hand or softness. Problems common with PVC/fabric laminate vanes are that in sunlight, the fabric may curl and delaminate, there is increased assembly costs, the vanes are relatively heavy and when the fabric is only laminated onto one face of the PVC, the reverse side is aesthetically displeasing. Another design includes a PVC vane core that is wrapped loosely with fabric. This provides a softer product with a fabric look, but it is very costly and difficult to fabricate. One other approach is a PVC vane with a groove along each edge so that a fabric insert can be positioned in and along the faces of the PVC vane. This approach is also costly, does not prevent longitudinal twisting and the reverse face and the grooved edges detract from the fabric appearance.
All of the prior art vertical vanes cast a distinct, well defined shadow on the adjacent vane when the vanes are completely closed and slightly overlapped in a window and are in direct sunlight. This shadow creates the effect of stripes on the surface of the closed vertical blind resulting in objectionable aesthetics.
Vanes, more commonly referred to as slats, found in Venetian blinds. as opposed to vertical blinds, typically have different qualities as they are disposed horizontally rather than vertically. In fact, some slats found in venetian blinds are of hollow construction. By way of example, U.S. Pat. No. 2,169,873 to W.D. Clark. Jr.; U.S. Pat. No. 2,326.454 to Scipio S. Gentile; and U.K. Pat. No. 623.832 assigned to Chr. Fabers Fabriker disclose hollow slats for use in a venetian blind. Since slats in venetian blinds are disposed horizontally, they must be self-supporting along their length. A self-supporting slat by its very nature must be somewhat rigid and therefore will not have a soft hand or feel. The venetian blind slat is rotated about a horizontal longitudinal axis by conventional tape ladders on which it is supported. This method of support does not require energy transfer from one end of the slat to the other as with vertical blinds. A vane in a vertical blind is supported from its top edge and is preferably rotated from its top edge. Therefore, it is not necessary that it be self supporting along its length. To rotate a vertical blind vane, energy must be transmitted from the top of the vane to the bottom in order for the entire vane to rotate. Uniform rotation along the entire length of the vane has been a problem with prior art vertical vanes.
Therefore, it is an object of the present invention to provide a vane for a vertical blind that is three-dimensional, has a soft hand or feel, that does not twist from top to bottom when rotated from the top but rather rotates uniformly, that hides the hanger of the carrier mechanism, and that diffuses the light passing through the shade so that no distinct, sharply defined shadows are formed.